fix(sites): preserve remote throttling reasons and HTTP diagnostics

行为对照：MoviePilot v3.2.4，6ca7b294/f4a68f36；复用现有站点共享桶，明确频控按远端秒数冷却，错误标题脱敏；修复有界响应读取对单个大数据块的限制。

packages/adapters/src/sites/challenge.ts

@@ -126,7 +126,7 @@ function concatBytes(chunks: Uint8Array[], total: number): Uint8Array<ArrayBuffe
 }
 
 /** 先读最多 max 字节;返回读到的部分、是否读完,以及一个内容不变的新响应(没读完的部分接着原流) */
-async function peekBody(
+export async function peekBody(
   res: Response,
   max: number,
 ): Promise<{ head: Uint8Array<ArrayBuffer>; complete: boolean; res: Response }> {
@@ -134,14 +134,17 @@ async function peekBody(
   const chunks: Uint8Array[] = [];
   let total = 0;
   let complete = false;
+  let remainder: Uint8Array | undefined;
   while (total < max) {
     const r = await reader.read();
     if (r.done) {
       complete = true;
       break;
     }
-    chunks.push(r.value);
-    total += r.value.byteLength;
+    const length = Math.min(r.value.byteLength, max - total);
+    chunks.push(r.value.subarray(0, length));
+    total += length;
+    if (length < r.value.byteLength) remainder = r.value.subarray(length);
   }
   const head = concatBytes(chunks, total);
   const init = { status: res.status, statusText: res.statusText, headers: res.headers };
@@ -149,6 +152,7 @@ async function peekBody(
   const stream = new ReadableStream<Uint8Array>({
     start(c) {
       c.enqueue(head);
+      if (remainder) c.enqueue(remainder);
     },
     async pull(c) {
       const r = await reader.read();